Bicycle hub transmission

ABSTRACT

A bicycle hub transmission basically includes a hub axle, a driver, a hub shell, a power transmission mechanism and a shift mechanism. The driver is rotatably supported relative to the hub axle. The hub shell is rotatably supported relative to the driver. The power transmission mechanism includes a downstream planetary gear unit and an upstream planetary gear unit disposed between the driver and the hub shell to selectively transmit rotational power from the driver to the hub shell through one a plurality of power transmission paths. The shift mechanism is operatively coupled to the power transmission mechanism to select one of the power transmission paths. The downstream planetary gear unit includes at least a first sun gear, a second sun gear and a planetary gear carrier that meshes with planetary gears of the upstream planetary gear unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to EuropeanPatent Application No. 07015124.6 filed Aug. 1, 2007. The entiredisclosure of European Patent Application No. 07015124.6 is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a hub transmission for abicycle. More specifically, the present invention relates to aninternally geared bicycle hub transmission.

2. Background Information

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One component that has been extensively redesigned is thebicycle drive train.

Internally mounted multi-speed hub transmissions are mounted to the rearwheel of a bicycle and allow a rider of the bicycle to select differentgear ratios to change the pedaling force. Typically a hub transmissionhas a hub axle that is mounted to the bicycle frame. The hub axlerotatably supports a driver for transmitting a pedaling force to the hubtransmission through a sprocket and a chain. The hub transmissionfurther comprises a hub shell which is likewise rotatably supported bythe hub axle.

The hub shell accommodates a power transmission mechanism which isdisposed between the driver and the hub shell for transmittingrotational power from the driver to the hub shell. The powertransmission mechanism provides a plurality of power transmission pathswith different gear ratios that can be selected by using a shiftmechanism, wherein each power transmission path typically produces aspecific gear ratio. To establish the plurality of power transmissionpaths the power transmission mechanism ordinarily has several planetarygear mechanisms.

Current internal hub transmissions are designed to provide 10 or morespeed stages. For example, one proposed internal hub transmission isdisclosed in German Patent Publication No. DE 10 2004 011 052 A1. Thehub transmission according to German Patent Publication No. DE 10 2004011 052 A1 allows a selection between 9 speed stages which are providedby a plurality of planetary gear mechanisms. The known hub transmissionhas three planetary gear mechanisms that allow the combination of threespeed stages with another five speed stages, for a total of nine speedstages with a gear ratio of 340%. The hub transmission includes a firstplanetary gear mechanism having a first sun gear that is non-rotatablymounted to the hub axle, a first planetary gear rotatably supported by afirst planetary gear carrier and a first ring gear. The first planetarygears are disposed between the first sun gear and the first ring gearand mesh with the same.

A second planetary gear mechanism includes a second sun gear which isarranged on the first planetary gear carrier. Second planetary gears aremounted on the first ring gear. A third planetary gear mechanism isformed similar to the second planetary gear mechanism, and includes athird sun gear mounted on the first planetary gear carrier. The thirdsun gear meshes with third planetary gears with each being non-rotatablyjoined to the respective second planetary gears. Thereby a two-stepplanetary gear is formed. The third planetary gears mesh with a secondring gear to transmit the torque of the third planetary gear mechanismto the second planetary gear mechanism.

The shifting mechanism of this hub transmission comprises a pawl carrierwhich allows coupling the driver selectively with components of therespective planetary gear mechanisms to produce different gear ratios.To this end the pawl carrier comprises a plurality of controllablepawls, namely six pawls that are actuated by means of three shiftingcams.

The arrangement of the two-step planetary gear on the first ring gear incombination with the second ring gear that meshes with the two-stepplanetary gears, leads to a pile type of internal hub transmission.Since the second ring gear overlaps the other components of the threeplanetary gear mechanisms, the diameter of the second ring gear and,thus, the diameter of the internal hub transmission is increased.Moreover, the pile type construction of the internal hub transmissionleads to an increased total weight of the hub.

As described above, the second and third sun gears are each mounted onthe first planetary gear carrier. Therefore, the second and third sungears each rotate together with the first planetary gear carrier aroundthe hub axle. In particular, the power transmission path for speedstages 8 and 9 comprises the driver, the sixth pawl and the firstplanetary gear carrier wherein the first planetary gears rotate aroundthe first sun gear. The power transmission path further has the firstring gear, the second ring gear, the first pawl, the pawl connecting thepower transmission with the hub shell and the hub shell. In speed stage8, the third planetary gear rotates around the third sun gear and inspeed stage 9 the second planetary gear rotates around the second sungear.

Due to this differential rotational type of the planetary gear mechanismthe power transmission paths are complicated. In particular the powertransmission paths for speed stages 8 and 9 inefficiently transmitpower.

A similar hub transmission is known from German Patent Publication No.DE 197 20 796 A1, which discloses a multiple speed hub having aplurality of planetary gear mechanisms arranged in series. The hubtransmission disclosed therein enables either a 7 speed shifting or a 14speed shifting. The 14 speed hub transmission comprises five planetarygear mechanisms, the components of which can be selectively locked toestablish the desired power transmission paths. A first planetary gearmechanism comprises a first sun gear rotatably supported by a hub axlewhich can be locked with the same. The first sun gear meshes with thesmaller diameter of a two-step planetary gear which is rotatablysupported by a first planetary gear carrier. The first planetary gearcarrier is non-rotatably connected with the hub shell. The largediameter of the two-step planetary gear meshes with a ring gear that canbe locked either with the hub axle or the first sun gear. A secondplanetary gear mechanism comprises a second sun gear rotatably supportedby and lockable with the hub axle. Second planetary gears mesh with thesun gear and a second ring gear wherein the second ring gear isnon-rotatably connected with the first sun gear. A third planetary gearmechanism comprises a third sun gear which is rotatably supported by andlockable with the hub axle. Third planetary gears mesh with the thirdsun gears which are non-rotatably connected with the second planetarygears with the respective second planetary gears. The second sun gearmeshes with the small diameter stage of the stepped planetary gears, andthe third sun gear meshes with the large diameter stage of the steppedplanetary gears.

The fourth and fifth planetary gear mechanisms are similar to the secondand third planetary gear mechanisms and are symmetrically formed andarranged. The fourth and fifth planetary gear mechanisms thereforelikewise comprise two-stage planetary gears, wherein the planetary gearsof the second and third planetary gear mechanism and the planetary gearsof the fourth and fifth planetary gear mechanisms are rotatablysupported by means of a common planetary gear carrier. The smalldiameter stage of the stepped planetary gears of the fourth and fifthplanetary gear mechanisms mesh with a ring gear that is non-rotatablyconnected with a driver.

A further embodiment of the 14-speed hub transmission is based on amodified embodiment of the above described hub transmission, and has asecond ring gear which meshes with both small diameter stages of thesymmetrically arranged stepped planetary gears. The common planetarygear carrier is replaced with two separate planetary gear carriers withthe planetary gear carrier of the second and third planetary gearmechanisms being non-rotatably connected with the first sun gear. Theplanetary gear carrier of the fourth and fifth planetary gear mechanismsis non-rotatably connected with the driver.

Owing to the increased number of clutches required for locking theseparate components of the planetary gear mechanisms, for example thering gears with the sun gears, the hub transmission according to GermanPatent Publication No. DE 197 20 796 A1 is complicated and comparativelyexpensive.

In view of the above, it will be apparent to those skilled in the artfrom this disclosure that there exists a need for an improved bicyclehub transmission. This invention addresses this need in the art as wellas other needs, which will become apparent to those skilled in the artfrom this disclosure.

SUMMARY OF THE INVENTION

One object of the invention to provide a hub transmission for a bicyclecomprising a plurality of speed stages and enabling a lightweight andcompact construction.

The foregoing object can basically be attained by providing a bicyclehub transmission that basically comprises a hub axle, a driver, a hubshell, a power transmission mechanism and a shift mechanism. The driveris rotatably supported relative to the hub axle. The hub shell isrotatably supported relative to the driver. The power transmissionmechanism includes a downstream planetary gear unit and an upstreamplanetary gear unit disposed between the driver and the hub shell toselectively transmit rotational power from the driver to the hub shellthrough one a plurality of power transmission paths. The shift mechanismis operatively coupled to the power transmission mechanism to select oneof the power transmission paths. The downstream planetary gear unitincludes at least a first sun gear, a second sun gear and a planetarygear carrier that meshes with planetary gears of the upstream planetarygear unit.

A hub transmission formed in accordance with the illustrated embodimenthas a number of advantages. Since the planetary gear carrier of thedownstream planetary gear unit meshes with planetary gears of theupstream planetary gear unit a compact design is achieved that allowsthe realization of a plurality of power transmission paths whilemaintaining a small diameter of the hub. The aforementioned coupling ofthe downstream planetary gear carrier with upstream planetary gearsfurther allows for a plurality of power transmission paths by using acomparatively simple structure that reduces the risk of failure ofcomponents in the transmission.

Owing to the surprisingly simple structure of the inventive hubtransmission, it is possible to produce a hub transmission that enablesa comparatively great number of gear ratios at relatively low costs.Since the downstream planetary gear unit comprises more than one sungear, the hub transmission according to the illustrated embodimentallows the implementation of 15 speed stages.

In a preferred embodiment, the power transmission mechanism has thedownstream planetary gear unit and the upstream planetary gear unitarranged to form at least five planetary gear mechanisms arranged inseries. Thereby it is possible to realize a 15-speed hub transmissionwith a compact design and a relatively small hub diameter.

Preferably, the downstream planetary gear unit constitutes at leastfirst and second planetary gear mechanisms and the upstream planetarygear unit constitutes at least third, fourth and fifth planetary gearmechanisms.

Preferably, the first and second planetary gear mechanisms include theplanetary gear carrier of the downstream planetary gear unit as a commoncarrier and the fourth gear mechanism includes the planetary gears ofthe upstream planetary gear unit. This means that the first and secondplanetary gear mechanisms are coupled with the fourth planetary gearmechanism by means of the planetary gear carrier of the downstreamplanetary gear unit which meshes with the upstream planetary gears.

Preferably, the planetary gear carrier of the downstream planetary gearunit includes a carrier portion and a ring gear portion which mesheswith the planetary gears of the upstream planetary gear unit, with thecarrier portion and the ring gear portion being non-rotatably connectedas a unit. Hence, it is to be emphasized that the planetary gear carrierof the downstream planetary gear unit fulfils two functions, namely asupport function for the planetary gears of the first and secondplanetary gear mechanisms and a power transmission function for theplanetary gears of the upstream planetary gear unit. Owing to thenon-rotatable connection between the carrier portion and the ring gearportion, the compact design of the hub transmission is optimized.

Preferably, the planetary gear carrier of the downstream planetary gearunit is selectively connectable with the fifth planetary gear mechanism.Thereby, a number of further power transmission paths can be realized.

The connection of the planetary gear carrier and the downstreamplanetary gear unit with the fifth planetary gear mechanism can berealized, for example, by means of a preferred embodiment wherein theplanetary gear carrier of the downstream planetary gear unit includes aclutch engaging portion which is selectively connectable with aplanetary gear carrier of the fifth planetary gear mechanism.

To enable transmission of a rotational force from the planetary gearcarrier of the downstream planetary gear unit to the hub shell, theplanetary gear carrier of the downstream planetary gear unit isselectively connectable with the hub shell by a first clutch to transmita rotational force from the planetary gear carrier to the hub shell.

In a preferred embodiment, the first planetary gear mechanism includesthe first sun gear and a plurality of first planetary gears, with thefirst sun gear being rotatably supported by the hub axle and selectivelylockable with the hub axle, and the first planetary gears beingrotatably supported by the planetary gear carrier of the downstreamplanetary gear unit and meshing with the first sun gear. The firstplanetary gear mechanism is part of the downstream planetary gear unit.

Preferably, the second planetary gear mechanism includes the second sungear, a first ring gear and a plurality of second planetary gears, withthe second sun gear being rotatably supported by the hub axle andselectively lockable with the hub axle, the first ring gear beingrotatably supported by the planetary gear carrier of the downstreamplanetary gear unit and being coaxially arranged with the second sungear, and the second planetary gears meshing with the second sun gearand the first ring gear, the second planetary gears and the first andsecond planetary gears being non-rotatably connected as a unit to formstepped planetary gears respectively. The second planetary gearmechanism is also part of the downstream planetary gear unit.

Thus, the downstream planetary mechanism comprises more than one sungear, namely the first and second sun gears. The first and second sungears of the downstream planetary gear unit (in general: the more thanone sun gear) mesh with the planetary gears of the first and secondplanetary gear mechanisms and interact with the (common) planetary gearcarrier of the downstream planetary gear unit.

Preferably, the first ring gear is selectively connectable with the hubshell by a second clutch for transmitting a rotational force from thefirst ring gear to the hub shell.

Preferably, the third planetary gear mechanism includes a third sungear, a second planetary gear carrier and a plurality of third planetarygears, with the third sun gear being rotatably supported by the hub axleand selectively lockable with the hub axle, the second planetary gearcarrier being rotatably supported relative to the hub axle and the thirdplanetary gears rotatably being supported by the second planetary gearcarrier and meshing with the third sun gear.

Preferably, the fourth planetary gear mechanism includes a fourth sungear rotatably supported by the hub axle and selectively lockable withthe hub axle, with the planetary gears of the fourth planetary gearmechanism being rotatably supported by the second planetary gear carrierand meshing with the fourth sun gear.

Preferably, the planetary gears of the fourth planetary gear mechanismand the third planetary gears of the third planetary gear mechanism arenon-rotatably connected as a unit to form stepped planetary gearsrespectively.

In a further preferred embodiment, the fifth planetary gear mechanismincludes a fifth sun gear, a second ring gear and a plurality of fifthplanetary gears, with the fifth sun gear being non-rotatably fixed tothe hub axle, the second ring gear being coaxially arranged with thefifth sun gear, and the fifth planetary gears being rotatably supportedby a third planetary gear carrier and meshing with the fifth sun gearand the second ring gear.

Preferably, the third planetary gear carrier engages with the secondplanetary gear carrier.

Preferably, a third clutch disposed between the third planetary gearcarrier and the first planetary gear carrier, with a clutch engagingportion arranged to selectively transmit a rotational force from thethird planetary gear carrier to the first planetary gear carrier. Afourth clutch can be disposed between the driver and the second ringgear to selectively transmit a rotational force from the driver to thesecond ring gear. A fifth clutch may be disposed between the driver andthe third planetary gear carrier to selectively transmit a rotationalforce from the driver to the third planetary gear carrier.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a longitudinal cross-sectional view of a hub transmissionaccording to an illustrated embodiment;

FIG. 2 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 1;

FIG. 3 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 2;

FIG. 4 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 3;

FIG. 5 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 4;

FIG. 6 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 5;

FIG. 7 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 6;

FIG. 8 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 7;

FIG. 9 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 8;

FIG. 10 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 9;

FIG. 11 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 10;

FIG. 12 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 11;

FIG. 13 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 12;

FIG. 14 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 13;

FIG. 15 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 14; and

FIG. 16 is a longitudinal cross-sectional view of the hub transmissionaccording to FIG. 1 in speed stage 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Selected embodiments of the present invention will now be explained withreference to the drawings. It will be apparent to those skilled in theart from this disclosure that the following descriptions of theembodiments of the present invention are provided for illustration onlyand not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

Referring initially to FIG. 1, a 15-speed bicycle hub transmission isillustrated in accordance with one preferred embodiment. The hubtransmission is configured and arranged be mounted to the rear wheel ofa bicycle. The hub transmission basically includes a hub axle 1 and adriver 2 which is rotatably supported by the hub axle 1. The hubtransmission further includes a hub shell 3 which is rotatably supportedby the hub axle 1. A power transmission mechanism 4 is disposed betweenthe driver 2 and the hub shell 3 to selectively transmit rotationalpower from the driver 2 to the hub shell 3 through one of a plurality ofpower transmission paths that can be selected to change the gear ratioas desired by the rider.

To select one of the power transmission paths a shift mechanism 5 isprovided. The shift mechanism 5 corresponds to the shift mechanismdescribed in detail in European Patent No. EP 1 323 627 A2 and U.S. Pat.No. 6,607,465 B1 mentioned therein. The hub transmission has a pluralityof planetary gear mechanisms 6, 7, 8, 9 and 10. The planetary gearmechanisms 6, 7, 8, 9 and 10 are arranged in series and form at leastfive planetary gear mechanisms in the illustrated embodiment. The higherthe number of the planetary gear mechanism 6, 7, 8, 9 or 10, the closerit is arranged to the driver 2. For example, the second planetary gearmechanism 7 is closer to the driver 2 than the first planetary gearmechanism 6.

As mentioned above, the power transmission mechanism 4 has the planetarygear mechanisms 6, 7, 8, 9 and 10 including a downstream planetary gearunit and an upstream planetary gear unit with the upstream planetarygear unit being arranged closer to the driver 2 than the downstreamplanetary gear unit. As seen in the direction of the rotational powerflow, the downstream planetary gear unit is arranged after the upstreamplanetary gear unit. For example, the downstream planetary gear unitincludes the first and second planetary gear mechanisms 6 and 7 and theupstream planetary gear unit includes the third, fourth and fifthplanetary gear mechanisms 8, 9 and 10. The first and second planetarygear mechanisms 6 and 7 (downstream planetary gear unit) can be coupledwith the fourth planetary gear mechanism 9 (upstream planetary gearunit).

As is evident from FIG. 1, the downstream planetary gear unit has aplanetary gear carrier 31, and the upstream planetary gear unit hasplanetary gears 44 with the planetary gear carrier 31 of the first andsecond planetary gear mechanisms 6 and 7 meshing with planetary gears 44of the fourth planetary gear mechanism 8. The planetary gear carrier 31is a common carrier for both the first and second planetary gearmechanisms 6 and 7.

In general, the planetary gear carrier 31 has a longitudinally extendingshape that is adapted to overlap components of the power transmissionmechanism 4 that are arranged upstream of the first and second planetarygear mechanisms 6 and 7 and, thus, more proximate to the driver 2 thanthe downstream planetary gear unit.

In particular, the planetary gear carrier 31 of the downstream planetarygear unit axially extends from the area of the first and secondplanetary gear mechanisms 6 and 7 to the area of the fourth planetarygear mechanism 9. As illustrated in FIG. 1, the planetary gear carrier31 axially extends over more than ⅓ to ½ of the entire length of the hubtransmission. The axial extension of the planetary gear carrier 31 issuch that the third planetary gear mechanism 8 which is arranged betweenthe second (downstream) planetary gear mechanism 7 and the fourthplanetary gear mechanism 9 is overlapped by the planetary gear carrier31. In the embodiment according to FIG. 1, the third planetary gearmechanism 8 is not engaged with the planetary gear carrier 31.

The planetary gear carrier 31 has a stepped shape with the innerdiameter of the subsequent steps increasing towards the driver 2. Thestepped shape of the planetary gear carrier 31 will be described in moredetail in conjunction with the respective components associated thereto.

The planetary gear carrier 31 further includes a (first) clutch engagingportion 31 c which is arranged on the axial end of the planetary gearcarrier 31 proximate to the driver 2. The clutch engaging portion 31 cis provided to engage with/disengage from the clutch 53 (third clutch)which will be described in more detail in connection with the fifthplanetary gear mechanism 10.

The planetary gear carrier 31 further has a ring gear portion. The ringgear portion 31 b is integrally connected with the clutch engagingportion 31 c and is formed with a smaller inner diameter than a clutchengaging portion 31 c. The ring gear portion 31 b meshes with theplanetary gears 44 of the upstream or fourth planetary gear mechanism 9.The inner diameter of the ring gear portion 31 b is larger than theouter diameter of third planetary gears 43 of the third planetary gearmechanism 8, to avoid engagement or collision therewith.

The ring gear portion 31 b is integrally connected with a carrierportion 31 a which supports first planetary gears 41 of the first(downstream) planetary gear mechanism 6 and the second planetary gears42 of the second (downstream) planetary gear mechanism 7. The firstplanetary gears 41 are rotatably supported by first planetary gearshafts 41 a. The second planetary gears 42 are rotatably supported bythe second planetary gear shafts 42 a. The first and second planetarygear shafts 41 a and 42 a are disposed in the carrier portion 31 a ofthe planetary gear carrier 31. Typically, three or more first planetarygears 41 are provided in the first planetary gear mechanism 6 and threeor more second planetary gears 42 are provided in the second planetarygear mechanism 7.

A further (or second) clutch engaging portion 31 d is integrally formedwith the carrier portion 31 a, and is provided for engagingwith/disengaging from a first clutch 51 to establish/interrupt a powertransmission from the planetary gear carrier 31 to the hub shell 3. Afurther (or second) clutch engaging portion 31 d is arranged downstreamof the first planetary gear mechanism 6. The ring gear portion 31 b andthe (first) clutch engaging portion 31 c are located upstream of theplanetary gear mechanism 6. Again, the downstream or upstreamarrangement of components is seen and to be understood in the directionof the power flow.

The plurality of planetary gear mechanisms 6, 7, 8, 9 and 10 will bedescribed in the following.

The first planetary gear mechanism 6 is arranged most downstream or mostdistant from the driver 2 with the first sun gear 11 being rotatablysupported by the hub axle 1 and selectively lockable with the hub axle1. Between an inner peripheral surface of the first sun gear 11 and thehub axle 1, the first sun gear guide ring 61 is non-rotatably fixed tothe hub axle 1. The first sun gear guide ring 61 allows for the lockingand unlocking of the first sun gear 11 by means of the shiftingmechanism 5.

The first planetary gears 41 are rotatably supported by the firstplanetary gear carrier 31, in particular by the first planetary gearshafts 41 a disposed in the first planetary gear carrier 31, and mesheswith the first sun gear 11.

The second planetary gear mechanism 7 is arranged upstream of the firstplanetary gear mechanism 6 with the second sun gear 12 being rotatablysupported by the hub axle 1 and selectively lockable with the hub axle1.

As seen in FIG. 1, the first sun gear 11 and the second sun gear 12 (ingeneral: the more than one or at least two sun gears) are arrangedadjacent or next to each other. The first and second sun gears 11 and 12(in general: the more than one or at least two sun gears) areselectively lockable with the hub axle 1. The first sun gear 11 and thesecond sun gear 12 form part of the downstream planetary gear unit whichis coupled with the planetary gears 44 of the upstream planetary gearunit or fourth planetary gear mechanism 9, by the first planetary gearcarrier 31.

As further seen in FIG. 1, the second sun gear 12 has an axialprojection 12 a which extends in a downstream axial direction. The axialprojection 12 a is arranged radially below the engaging portion of thefirst sun gear 11 which meshes with the first planetary gears 41. Tothis end, the sun gear 11 has a shoulder which accommodates the axialprojection 12 a of the second sun gear 12. Thereby, a compact and stableconfiguration of the first and second sun gears 11 and 12 is achieved.

The second planetary gear mechanism 7 further has the second planetarygears 42 which mesh with second sun gear 12. Coaxially arranged inrelation to and rotatably supported by the hub axle 1, is a first ringgear 21 which meshes with second planetary gears 42 of the secondplanetary gear mechanism 7. Thus, the second planetary gears 42 arearranged in between the first ring gear 21 and the second sun gear 12.The second planetary gears 42 are supported by second planetary gearshafts 42 a. The second planetary gear shafts 42 a are disposed in thefirst planetary gear carrier 31.

The second planetary gear shaft 42 a is integrally formed with the firstplanetary gear shaft 41 a such that the first and second planetary gears41 and 42 are supported by the same or a common shaft 41 a or 42 a.

As illustrated in FIG. 1, the first and second planetary gears 41 and 42form two gear stages wherein the large diameter gear stage of the firstplanetary gear 41 meshes with the first sun gear 11 and the smalldiameter gear stage of the second planetary gear 42 meshes with thefirst ring gear 21. The small diameter gear stage of the secondplanetary gears 42 is arranged proximate to the third planetary gearmechanism 8. The first and second planetary gears 41 and 42 arenon-rotatably coupled, in particular integrally formed.

Thereby, the first and second planetary gears 41 and 42 constitute astepped or non-rotatably coupled planetary gear comprising two differentdiameters, which mesh with the first and second sun gears 11 and 12 (ingeneral: with the at least two sun gears 11 and 12). The large diameterof the stepped planetary gear meshes with the first sun gear 11 and thesmall diameter of the stepped planetary gear meshes with the second sungear 12 and the first ring gear 21.

The two sun gears 11 and 12 can be coupled by the first planetary gearcarrier 31 with an upstream planetary gear unit, in particular with thefourth planetary gear mechanism 9.

The first ring gear 21 can be connected with or disconnected from thehub shell 3 by a second (one-way) clutch 52 which is disposed betweenthe first ring gear 21 and the hub shell 3.

As described above, the ring gear carrier 31 of the first planetary gearmechanism 6 extends axially beyond the first and second planetary gears41 and 42 in a longitudinal direction of the hub transmission therebyoverlapping at least the subsequently arranged upstream third and fourthplanetary gear mechanisms 8 and 9. The outer contour of first planetarygear carrier 31 is adapted to partially accommodate the first ring gear21 and forms the shoulder 31 e such that the first ring gear 21 isarranged between the shoulder 31 e and the large diameter gear stage ofthe first planetary gears 41.

The third planetary gear mechanism 8 is located upstream of the secondplanetary gear mechanism 7 with the third sun gear 13 being rotatablysupported by the hub axle 1 and selectively lockable with the hub axle1. Between an inner surface of the second sun gear 13 and the hub axle1, the third sun gear guide ring 63 is non-rotatably fixed to the hubaxle 1. Several third planetary gears 43 are rotatably supported by asecond planetary gear carrier 32 which is rotatably supported by the hubaxle 1. To this end, the third planetary gears 43 are rotatablysupported by the third planetary gear shafts 43 a which are supported bythe second planetary gear carrier 32. Typically three or more thirdplanetary gears 43 are provided.

The fourth planetary gear mechanism 8 is arranged upstream of the thirdplanetary gear mechanism 8 with the fourth sun gear 14 being rotatablysupported by the hub axle 1 and selectively lockable with the hub axle1. Between an inner peripheral surface of the fourth sun gear 13 and thehub axle 1, the fourth sun gear guide ring 64 is arranged andnon-rotatably fixed to hub axle 1. The fourth sun gear guide ring 64 canbe actuated by means of the shifting mechanism 5 to lock/unlock thefourth sun gear 14.

Several fourth planetary gears 44 mesh with the fourth sun gear 14, andis rotatably supported by the second planetary gear carrier 32. Inparticular, fourth planetary gears 44 are arranged on a fourth planetarygear shaft 44 a which is integrally formed with the third planetary gearshaft 43 a and, thus, represents a common planetary gear shaft for thethird and fourth planetary gears 43 and 44.

As is evident from FIG. 1, the third and fourth planetary gears 43 and44 are non-rotatably connected and integrally form a stepped planetarygear 402. The small diameter gear stage of the stepped planetary gear402 (third planetary gears 43) meshes with the third sun gear 13, andthe large diameter gear stage of the stepped planetary gear 402 (fourthplanetary gears 44) meshes with the fourth sun gear 9. Moreover, thelarge diameter gear stage of the stepped planetary gear 402 (fourthplanetary gears 44) meshes with the ring gear portion 31 b of thedownstream planetary gear carrier 31. Thus, it is possible to establisha transmission path connecting the fourth sun gear 9 with the firstplanetary gear carrier 31.

The fifth planetary gear mechanism 10 is arranged upstream of the fourthplanetary gear mechanism 9 and represents the planetary gear mechanismclosest to the driver 2. The fifth planetary gear mechanism 10 has thefifth sun gear 15 which is non-rotatably fixed to the hub axle 1. Thesecond ring gear 22 is coaxially arranged with and rotatably supportedby the hub axle 1. Between the second ring gear 22 and the fifth sungear 15, the fifth planetary gears 45 are arranged which are formed astwo-step planetary gears. The large diameter gear stage of the fifthplanetary gears 45 meshes with the second ring gear 22, and the smalldiameter gear stage of the fifth planetary gears 45 meshes with thefifth sun gear 15. Typically three or more fifth planetary gears 45 areprovided.

The fifth planetary gears 45 are rotatably supported by a thirdplanetary gear carrier 33 which can rotate around the hub axle 1. Thethird planetary gear carrier 33 has the fifth planetary gear shafts 45 awhich rotatably support the fifth planetary gears 45. The thirdplanetary gear carrier 33 is engaged with the second planetary gearcarrier 32 to transmit power from the third planetary gear carrier 33 tothe second planetary gear carrier 32.

As is readily apparent from FIG. 1, the middle axes of the third andfourth planetary gear shafts 43 a and 44 a and the middle axes of thefifth planetary gear shafts 45 a are radially spaced apart. The middleaxes of fifth planetary gear shafts 45 a are arranged on a cylindricalplane having a larger diameter than a cylindrical plane which comprisesthe middle axes of the third and fourth planetary gear shafts 43 a and44 a. The cylindrical plane which comprises the middle axes of first andsecond planetary gear shafts 41 a and 42 a corresponds to thecylindrical plane of the middle axes of the fifth planetary gear shafts45 a. Thus, the middle axes of the third and fourth planetary gearshafts 43 a and 44 a, which are arranged between the second and fifthplanetary gear mechanisms 7 and 10, are closer to the hub axle 1 thanthe middle axes of the second and fifth planetary gear shafts 42 a and45 a, respectively.

The third planetary gear carrier 33 of the fifth planetary gearmechanism 9 can be connected to the downstream planetary gear carrier31. For this purpose, the third clutch 53 mentioned above is providedbetween the third planetary gear carrier 33 and the first planetary gearcarrier 31. In particular, the third clutch 53 is arranged at an end ofthe third planetary gear carrier 33 distant from the driver 2 andengages with/disengages from the clutch engaging portion 31 c ofdownstream of the first planetary gear carrier 31. For the powertransmission from the driver 2 to the fifth planetary gear mechanism 9,the fourth and fifth clutches 54 and 55 are provided.

The fourth clutch 54 is a one-way clutch disposed between the driver 2and the second ring gear 22. The second ring gear 22 comprises an axialprojection 22 a which extends towards the driver 2. The axial projection22 a comprises on its inner peripheral surface a clutch engaging portion22 b, which cooperates with the fourth clutch 54 to lock or unlock thesecond ring gear 22 with the driver 2. The fourth clutch 54 is supportedby the axial projection 2 a of the driver 2 that extends in parallelwith the axial projection 22 a of the ring gear 22.

For speed stages 1 to 6, the fourth clutch 54 is engaged with the ringgear 22 to transmit power from the driver 2 to the ring gear 22.

For speed stages 7 to 11, the fifth clutch 55 is provided which isdisposed between the driver 2 and the third planetary gear carrier 33for transmitting rotational power from the driver 2 to the thirdplanetary gear driver 33. The fifth clutch 55 is formed as a clutchring, and is axially movable in a longitudinal direction of the hub axle1. The fifth clutch 55 has the two engaging portions 55 a and 55 b whichare adapted to engage with the clutch engaging portions 2 b and 33 awhich are provided on the driver 2 and the third planetary gear carrier33, respectively.

The clutch engaging portion 2 b of the driver 2 is formed on the innerperipheral surface of the axial projection 2 a and engages with theupper or radial engaging portion 55 b of the fifth clutch 55. The clutchengaging portion 33 a of the third planetary gear carrier 33 is adaptedto engage with/disengage from the lower or axial engaging portion 55 aof the fifth clutch 55.

For speed stages 7 to 11, the axial engaging portion 55 a of the fifthclutch 55 and the clutch engaging portion 33 a of the third planetarygear carrier 33 are coupled and the fourth clutch 54 is uncoupled. Amore detailed description of the aforementioned clutch mechanismincluding the fourth and fifth clutches 54 and 55 is disclosed inEuropean Patent No. EP 1 323 627 A2 as well as in European PatentApplication No. 07 001 076.4, both assigned to Shimano Inc.

The function of the hub transmission according to FIG. 1 is explainedwith reference to FIGS. 2 to 16 in which the coupling of the variouscomponents for each speed stage and the specific power transmission pathrealized thereby are illustrated. The bold lines and arrows indicated inFIGS. 2 to 16 illustrate the rotational power flow through the powertransmission mechanism 4. The coupling of the various components as wellas the power transmission paths are indicated in the following Tables 1and 2 wherein Table 1 concerns the coupling of the components and Table2 concerns the specific power transmission path.

TABLE 1 Clutch ring 55 Speed (Driver and 3rd Planetary First SecondThird Fourth Stage gear carrier 33) Sun gear 11 Sun gear 12 Sun gear 13Sun gear 14 1 Disengaged Free Free Free Free 2 Disengaged Locked FreeFree Free 3 Disengaged Free Free Free Locked 4 Disengaged Free FreeLocked Free 5 Disengaged Locked Free Free Locked 6 Disengaged LockedFree Locked Free 7 Disengaged Free Locked Free Locked 8 Disengaged FreeLocked Locked Free 9 Disengaged Locked Free Free Free 10 Disengaged FreeFree Free Locked 11 Disengaged Free Free Locked Free 12 DisengagedLocked Free Free Locked 13 Disengaged Locked Free Locked Free 14Disengaged Free Locked Free Locked 15 Disengaged Free Locked Locked Free

TABLE 2 Speed Gear Stage Power Transmission Path Ratio 1 Driver - 4thclutch 54 - 2nd ring gear 22 - (5th planet gear 45 rotates around 5th0.426 sun gear 15) - 3rd planetary gear carrier 33- 3rd clutch 53 - 1stplanetary carrier 31 - 1st clutch 51 - Hub Shell 2 Driver - 4th clutch54 - 2nd ring gear 22 - (5th planet gear 45 rotates around 5th 0.545 sungear 15) - 3rd planetary gear carrier 33 - 3rd clutch 53 - 1st planetarycarrier 31 - (1st planet gear 41 rotates around 1st sun gear 11) - 1string gear 21 - 2nd clutch 52 - Hub Shell 3 Driver - 4th clutch 54 - 2ndring gear 22 - (5th planet gear 45 rotates around 0.612 5th sun gear15) - 3rd planetary gear carrier 33- 2nd planetary gear carrier 32 -(4th planet gear 44 rotates around 4th sun gear 14) - 1st planetary gearcarrier 31 - 1st clutch 51 - Hub Shell 4 Driver - 4th clutch 54 - 2ndring gear 22 - (5th planet gear 45 rotates around 0.694 5th sun gear15) - 3rd planetary gear carrier 33 - 2nd planetary gear carrier 32 -(3rd planet gear 43 rotates around 3rd sun gear 13) - 1st planetary gearcarrier 31 - 1st clutch 51 - Hub Shell 5 Driver - 4th clutch 54 - 2ndring gear 22 - (5th planet gear 45 rotates around 0.782 5th sun gear15) - 3rd planetary gear carrier 33 - 2nd planetary gear carrier 32 -(4th planet gear 44 rotates around 4th sun gear 14) - 1st planetarycarrier 31 - (1st planet gear 41 rotates around 1st sun gear 11) - 1string gear 21 - 2nd clutch 52 - Hub Shell 6 Driver - 4th clutch 54 - 2ndring gear 22 - (5th planet gear 45 rotates around 0.887 5th sun gear15) - 3rd planetary gear carrier 33 - 2nd planetary gear carrier 32 -(3rd planet gear 43 rotates around 3rd sun gear 13) - 1st planetarycarrier 31 - (1st planet gear 41 rotates around 1st sun gear 11) - 1string gear 21 - 2nd clutch 52 - Hub Shell 7 Driver - 4th clutch 54 - 2ndring gear 22 - (5th planet gear 45 rotates around 0.997 5th sun gear15) - 3rd planetary gear carrier 33 - 2nd planetary gear carrier 32 -(4th planet gear 44 rotates around 4th sun gear 14) - 1st planetarycarrier 31 - (2nd planet gear 42 rotates around 2nd sun gear 12) - 1string gear 21 - 2nd clutch 52 - Hub Shell 8 Driver - 4th clutch 64 - 2ndring gear 22 - (5th planet gear 45 rotates around 1.130 5th sun gear15) - 3rd planetary gear carrier 33 - 2nd planetary gear carrier 32 -(3rd planet gear 43 rotates around 3rd sun gear 13) - 1st planetarycarrier 31 - (2nd planet gear 42 rotates around 2nd sun gear 12) - 1string gear 21 - 2nd clutch 52 - Hub Shell 9 Driver - 5th clutch 55 - 3rdplanetary gear carrier 33 - 3rd clutch 53 - 1st 1.279 planetary carrier31 - (1st planet gear 41 rotates around 1st sun gear 11) - 1st ring gear21 - 2nd clutch 52 - Hub Shell 10 Driver - 5th clutch 55 - 3rd planetarygear carrier 33 - 2nd planetary gear carrier 1.437 32 - (4th planet gear44 rotates around 4th sun gear 14) - 1st planetary gear carrier 31 - 1stclutch 51 - Hub Shell 11 Driver - 5th clutch 55 - 3rd planetary gearcarrier 33 - 2nd planetary gear carrier 1.630 32 - (3rd planet gear 43rotates around 3rd sun gear 13) - 1st planetary gear carrier 31 - 1stclutch 51 - Hub Shell 12 Driver - 5th clutch 55 - 3rd planetary gearcarrier 33 - 2nd planetary gear carrier 1.838 32 - (4th planet gear 44rotates around 4th sun gear 14) - 1st planetary carrier 31 - (1st planetgear 41 rotates around 1st sun gear 11) - list ring gear 21 - 2nd clutch52 - Hub Shell 13 Driver - 5th clutch 55 - 3rd planetary gear carrier33 - 2nd planetary gear carrier 2.085 32 - (3rd planet gear 43 rotatesaround 3rd sun gear 13) - 1st planetary carrier 31 - (1st planet gear 41rotates around 1st sun gear 11) - 1st ring gear 21 - 2nd clutch 52 - HubShell 14 Driver - 5th clutch 55 - 3rd planetary gear carrier 33 - 2ndplanetary gear carrier 2.341 32 - (4th planet gear 44 rotates around 4thsun gear 14) - list planetary carrier 31 - (2nd planet gear 42 rotatesaround 2nd sun gear 12) - 1st ring gear 21 - 2nd clutch 52 - Hub Shell15 Driver - 5th clutch 55 - 3rd planetary gear carrier 33 - 2ndplanetary gear carrier 2.656 32 - (3rd planet gear 43 rotates around 3rdsun gear 13) - 1st planetary carrier 31 - (2nd planet gear 42 rotatesaround 2nd sun gear 11) - 1st ring gear 21 - 2nd clutch 52 - Hub Shell

In summary, the hub transmission according to the described embodimentof the invention allows the realization of an 11 speed internal hubtransmission wherein the diameter of the hub shell 2 is similar to thediameter of a currently available 8 speed hub transmission. This meansthat the hub transmission of the invention provides more speed stagesthan the conventional hub transmission without increasing the hubdiameter. Moreover, the hub transmission according to FIG. 1 providesthe advantage that all transmission paths are simple which leads to anefficient power transmission.

In general, the planetary gear carrier 31 of the downstream planetarygear mechanism 6 has an axially elongated shape adapted to mesh with theplanetary gears 43 of the upstream planetary gear mechanism 8. Moreover,the axially elongated shape of the planetary gear carrier 31 allows forcoupling/uncoupling the planetary gear carrier 31 with/from a planetarygear carrier 33 of a further upstream planetary gear mechanism 9. Inparticular, the axially elongated planetary gear carrier 31 of thedownstream planetary gear mechanism 6 is adapted to selectively transmitrotational power from the planetary gears 43 of the upstream planetarygear mechanism 8 and to selectively transmit rotational power from theplanetary gear carrier 33 of the further upstream planetary gearmechanism 9.

The axially elongated shape of the downstream planetary gear carrier 31allows for a compact, small diameter internal hub transmission for abicycle with highly efficient transmission paths.

General Interpretation of Terms

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. For example, the size, shape, location ororientation of the various components can be changed as needed and/ordesired. Components that are shown directly connected or contacting eachother can have intermediate structures disposed between them. Thefunctions of one element can be performed by two, and vice versa. Thestructures and functions of one embodiment can be adopted in anotherembodiment. It is not necessary for all advantages to be present in aparticular embodiment at the same time. Every feature which is uniquefrom the prior art, alone or in combination with other features, alsoshould be considered a separate description of further inventions by theapplicant, including the structural and/or functional concepts embodiedby such feature(s). Thus, the foregoing descriptions of the embodimentsaccording to the present invention are provided for illustration only,and not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

1. A bicycle hub transmission comprising: a hub axle; a driver rotatablysupported relative to the hub axle; a hub shell rotatably supportedrelative to the driver, a power transmission mechanism including adownstream planetary gear unit and an upstream planetary gear unit,which are operatively disposed between the driver and the hub shell toselectively transmit rotational power from the driver to the hub shellthrough one a plurality of power transmission paths; and a shiftmechanism operatively coupled to the power transmission mechanism toselect one of the power transmission paths, the downstream planetarygear unit including at least a first sun gear, a second sun gear and aplanetary gear carrier that meshes with planetary gears of the upstreamplanetary gear unit.
 2. The bicycle hub transmission according to claim1, wherein the downstream planetary gear unit and the upstream planetarygear unit form at least five planetary gear mechanisms arranged inseries.
 3. The bicycle hub transmission according to claim 1, whereinthe downstream planetary gear unit constitutes at least first and secondplanetary gear mechanisms and the upstream planetary gear unitconstitutes at least third, fourth and fifth planetary gear mechanisms.4. The bicycle hub transmission according to claim 3, wherein the firstand second planetary gear mechanisms include the planetary gear carrierof the downstream planetary gear unit as a common carrier and the fourthgear mechanism includes the planetary gears of the upstream planetarygear unit.
 5. The bicycle hub transmission according to claim 1, whereinthe planetary gear carrier of the downstream planetary gear unitincludes a carrier portion and a ring gear portion which meshes with theplanetary gears of the upstream planetary gear unit, with the carrierportion and the ring gear portion being non-rotatably connected as aunit.
 6. The bicycle hub transmission according to claim 3, wherein theplanetary gear carrier of the downstream planetary gear unit isselectively connectable with the fifth planetary gear mechanism.
 7. Thebicycle hub transmission according to claim 6, wherein the planetarygear carrier of the downstream planetary gear unit includes a clutchengaging portion which is selectively connectable with a planetary gearcarrier of the fifth planetary gear mechanism.
 8. The bicycle hubtransmission according to claim 1, wherein the planetary gear carrier ofthe downstream planetary gear unit is selectively connectable with thehub shell by a first clutch to transmit a rotational force from theplanetary gear carrier to the hub shell.
 9. The bicycle hub transmissionaccording to claim 8, wherein the first planetary gear mechanismincludes the first sun gear and a plurality of first planetary gears,with the first sun gear being rotatably supported by the hub axle andselectively lockable with the hub axle, and the first planetary gearsbeing rotatably supported by the planetary gear carrier of thedownstream planetary gear unit and meshing with the first sun gear. 10.The bicycle hub transmission according to claim 3, wherein the secondplanetary gear mechanism includes the second sun gear, a first ring gearand a plurality of second planetary gears, with the second sun gearbeing rotatably supported by the hub axle and selectively lockable withthe hub axle, the first ring gear being rotatably supported by theplanetary gear carrier of the downstream planetary gear unit and beingcoaxially arranged with the second sun gear, and the second planetarygears meshing with the second sun gear and the first ring gear, thesecond planetary gears and the first and second planetary gears beingnon-rotatably connected as a unit to form stepped planetary gearsrespectively.
 11. The bicycle hub transmission according to claim 10,wherein the first ring gear is selectively connectable with the hubshell by a second clutch for transmitting a rotational force from thefirst ring gear to the hub shell.
 12. The bicycle hub transmissionaccording to claim 11, wherein the third planetary gear mechanismincludes a third sun gear, a second planetary gear carrier and aplurality of third planetary gears, with the third sun gear beingrotatably supported by the hub axle and selectively lockable with thehub axle, the second planetary gear carrier being rotatably supportedrelative to the hub axle and the third planetary gears rotatably beingsupported by the second planetary gear carrier and meshing with thethird sun gear.
 13. The bicycle hub transmission according to claim 12,wherein the fourth planetary gear mechanism includes a fourth sun gearrotatably supported by the hub axle and selectively lockable with thehub axle, with the planetary gears of the fourth planetary gearmechanism being rotatably supported by the second planetary gear carrierand meshing with the fourth sun gear.
 14. The bicycle hub transmissionaccording to claim 13, wherein the planetary gears of the fourthplanetary gear mechanism and the third planetary gears of the thirdplanetary gear mechanism are non-rotatably connected as a unit to formstepped planetary gears respectively.
 15. The bicycle hub transmissionaccording to claim 14, wherein the fifth planetary gear mechanismincludes a fifth sun gear, a second ring gear and a plurality of fifthplanetary gears, with the fifth sun gear being non-rotatably fixed tothe hub axle, the second ring gear being coaxially arranged with thefifth sun gear, and the fifth planetary gears being rotatably supportedby a third planetary gear carrier and meshing with the fifth sun gearand the second ring gear.
 16. The bicycle hub transmission according toclaim 15, wherein the third planetary gear carrier engages with thesecond planetary gear carrier.
 17. The bicycle hub transmissionaccording to claim 15, further comprising a third clutch disposedbetween the third planetary gear carrier and the first planetary gearcarrier, with a clutch engaging portion arranged to selectively transmita rotational force from the third planetary gear carrier to the firstplanetary gear carrier.
 18. The bicycle hub transmission according toclaim 17, further comprising a fourth clutch is disposed between thedriver and the second ring gear to selectively transmit a rotationalforce from the driver to the second ring gear.
 19. The bicycle hubtransmission according to claim 18, further comprising a fifth clutch isdisposed between the driver and the third planetary gear carrier toselectively transmit a rotational force from the driver to the thirdplanetary gear carrier.